Circuit board includes a copper conductive circuit layer, and a plating film attached to the copper conductive circuit layer. The plating film includes a nickel layer attached to the copper conductive circuit layer, and a gold layer attached to the nickel layer. The plating film can have fractured surface. Sometimes the fractured surface exposes the copper conductive circuit layer, the nickel layer, and the gold layer. When the fractured surface is exposed in a damp H2S gas atmosphere, the copper will react with the H2S as follows: H2SH++HS−, Cu+O2→Cu2+O, Cu2+O+H2S→Cu2S↓+H2O, Cu2+O+O2→CuO, CuO+H2S→CuS↓+H2O, thus the copper conductive circuit layer will be corroded. Galvanic cell effect can occur at the interface of gold and nickel, and an interface of nickel and copper, to cause the nickel layer and the copper conductive circuit layer to corrode, thus the gold layer will fall off. Thus a new circuit board in which the nickel layer and the copper conductive circuit layer cannot be corroded is preferred.